Guidescope: How Ad Blocking Works

How Ad Blocking Works

How does ad blocking work?

The Guidescope service blocks graphical ads using a central database augmented by pattern matching:

Database: Our database keeps a record of graphical ads that have been identified and blocked by our users. Whenever you go to a new page, our database sends your computer a list of ads known to be on that page. Then when your browser downloads that page, it skips over the ads in the list. Because those ads are never downloaded, the page loads faster.

Pattern Matching: We use pattern matching to block ads from "ad servers" that place ads on many popular Web sites. Because ad servers are easily recognized, pattern matching works well for blocking ads that come from them.

Because we use a combination of pattern matching and a database, we are able to block ads that slip through all other ad-filtering products. Other products rely solely on pattern matching techniques and are unable to block ads that don't match their patterns. Their pattern lists are updated infrequently (or never), letting even more ads slip through. Our database is updated continuously and works with our pattern matching. Therefore, we block ads that others miss.

How do ads get into the database?

Whenever a user identifies and blocks a new ad or other unwanted graphic using the Ad List, it is immediately blocked on that user's computer. It is also submitted for inclusion in our database. As soon as a critical mass of users that have seen the ad have also blocked it, we add it to our database. Once an ad is in our database it is automatically blocked for all users.

What about ads on "secure" sites that use SSL?

To protect your privacy and maintain security, we do not block ads on or examine data streams associated with pages of Internet sites that use SSL (Secure Sockets Layer) an option commonly used on order forms that collect personal information such as collect credit numbers.

What do blocked ads look like?

Guidescope gives you control over how a blocked graphic "appears". You can either have your browser draw an outlined icon in place of the blocked graphic or you can have it leave a blank space where the blocked graphic would have been. In both cases, the blocked graphic is not downloaded. The appearance of blocked graphics is set as part of your User Profile.